Sample preparation involving enrichment of target nucleic acid molecules from samples or reaction mixtures is frequently required prior to downstream applications such as cloning and nucleic acid sequencing. Typically, such downstream applications are performed in high throughput format, increasing the labor, time, and reagent costs for sample preparation prior to such techniques. Such applications frequently require the starting amounts and/or concentrations of nucleic acid molecule sample inputs to be normalized (or standardized) within an optimal working range. For example, many applications require normalization of nucleic acid samples before analysis can be performed, the purpose of such normalization being to substantially equalize the number of nucleic acid molecules (or concentration of nucleic acid molecules) within each sample to each other. These steps of quantification and normalization are extremely time-consuming and tedious; and strain laboratory resources as the number of target nucleic acid libraries to be quantified and/or normalized increases. Typically, to quantify a target nucleic acid library an aliquot of each sample is diluted and the nucleic acid concentration is determined. If the concentration of either or both samples varies significantly from the acceptable working range, the samples can be diluted or otherwise adjusted to acceptable starting amounts or concentrations. In some instances, the nucleic acid concentrations are adjusted to be substantially equal to each other during the normalization process. This process is referred to as “normalization” resulting in the generation of normalized samples having substantially equal numbers (or concentrations) of nucleic acid molecules. Such quantification and/or normalization processes, in addition to being labor-intensive, also impede the speed by which other downstream process can be initiated. In some instances, the time required to quantify and normalize several thousand target nucleic acid libraries can ultimately influence the speed by which sequencing data can be obtained from such downstream processes. Therefore, what is needed is an improved method for normalizing the starting number and/or concentration of nucleic acid molecules within one or more samples. What is also needed is a method by which to purify an extended primer product from a primer extension reaction mixture. Further, a method for isolating a specific amount of nucleic acid from a sample is desired.